Search PubMed⌕ Search

Biomedical subjects

S Bharati

Publications and source records attributed to S Bharati.

At least 91 records · Page 5Linked to original sources
PubMed1987

Closed chest catheter desiccation of the atrioventricular junction using radiofrequency energy--a new method of catheter ablation.

Closed chest catheter ablation of the atrioventricular (AV) junction has been performed with direct current or laser energy. The effect of 750 kHz radiofrequency energy on ablation of the AV junction was evaluated in 13 dogs. The radiofrequency energy was generated from an electrosurgical generator in the bipolar mode. The radiofrequency output was delivered between two distal electrodes (bipolar ablation) in eight dogs, and between the distal electrode and an external patch electrode (unipolar ablation) in another five dogs at varying power (watts) but with a constant pulse duration of 10 seconds. Complete AV block was achieved in 11 dogs and second degree AV block in 2. During the 4 to 7 day follow-up period, complete AV block persisted in 9 of the 11 dogs with initial complete heart block. The other two had return of AV conduction; one had persistent 2:1 AV block and the other had persistent first degree AV block. Of the two dogs with initial second degree AV block, one developed complete AV block, the other had resumption of 1:1 AV conduction with a normal PR interval. Energy was delivered in 1 to 13 applications per dog. One hundred to 700 J per application was delivered with bipolar ablation and 10 to 100 J with unipolar ablation. There was no damage to the catheter unless the catheter was repeatedly used in excess of 1,500 J of total energy. Ventricular arrhythmias were not observed. Pathologic examination showed well delineated coagulation necrosis at the AV junction without surrounding hemorrhage or mural thrombus. Microscopic findings consisted of necrosis with cell infiltration in the periphery of necrosis. Most injuries involved the AV node, the approaches to the AV node and the penetrating bundle. In conclusion, catheter ablation of the AV junction with radiofrequency energy is safe. It can effectively induce discrete areas of necrosis and produce various degrees of AV block. In addition, ablation by radiofrequency energy has distinct advantages as compared with catheter ablation with direct current or laser energy.

Animals↗
PubMed1987

Electrophysiologic and histologic observations of chronic atrioventricular block induced by closed-chest catheter desiccation with radiofrequency energy.

Direct-current or laser energy has been used to induce atrioventricular (AV) block, but certain complications associated with this type of energy have been reported. We have previously documented that radiofrequency (RF) energy can effectively and safely induce acute AV block in closed-chest dogs during the 4-7 days of follow-up. This study was undertaken to determine if the ablation was permanent and to define the chronic pathology and site of AV block. Complete AV block was successfully achieved in four dogs immediately after ablation with a bipolar "standard" RF output (750 kHz) delivered between the tip electrode of a standard 7F USCI catheter and an external patch electrode on the left lateral chest wall. During 2 months of follow-up, three dogs had persistent complete AV block with a stable escape rhythm; the other had persistent 2:1 AV block. Repeat His bundle recordings were performed at 2 months prior to sacrifice of the dogs. Supra-His AV block was noted in two dogs; His bundle potential could not be recorded in another two. Histologically, the damaged area was well delineated. In all animals, the AV node and, in some dogs, part of the His bundle were completely replaced by granulation tissue and/or cartilage. There was fatty infiltration and also chronic inflammatory cells around the lesions. Neither perforation, hemorrhage nor vacuolation was seen in the adjacent area. Thrombus was not present. It is concluded that RF energy can effectively achieve chronic AV block and produce well-circumscribed pathological lesions.

Animals↗
PubMed1987

Neonatal lupus with congenital atrioventricular block and myocarditis.

This is a case of a child with neonatal lupus and congenital atrioventricular (AV) block, born to a mother with asymptomatic, systemic lupus erythematosus (SLE). The child, despite pacemaker insertion, died of septicemia and myocarditis at the age of three months. Although the association of neonatal lupus with congenital AV block is well-recognized, there are only few pathologic studies of the conduction system reported in the literature. This is such a study in which we emphasize that, due to an altered immune system in the child, septicemia may be the cause of death in some cases.

Female↗
PubMed1987

Low-energy transvenous ablation of the canine atrioventricular conduction system with a suction electrode catheter.

A single suction electrode catheter was used for His bundle electrogram recording. His bundle pacing, and low-energy (20 or 30 J) His bundle ablation in seven dogs. The suction electrode catheter was actively fixed to the atrial endocardium at the His bundle level. Electrophysiologic studies were performed in the control state, immediately after, and late (greater than 40 days) after His bundle ablation and results were correlated with histologic findings in the conduction system. Unipolar His bundle recording and pacing were successfully performed in all dogs with the suction electrode catheter before and after ablation. Complete heart block developed after a single 20 J shock delivered via the suction electrode catheter in all dogs immediately, but reverted to 1:1 atrioventricular conduction with first-degree atrioventricular block in two dogs in which one or two additional shocks (20 or 30 J) produced complete heart block. Mean ablation energy per shock was 22 +/- 4 J. The mean total delivered energy per dog was 31 +/- 20 J. Late electrophysiologic study in all dogs showed persistent complete heart block in five dogs and paroxysmal second-degree or third-degree atrioventricular block in two dogs. Gross examination of the ablation site showed a white plaque above the medial tricuspid leaflet (1.4 to 2.0 cm long and 0.4 to 0.6 cm wide). Microscopically, fibrosis of the penetrating and branching His bundle was seen in all dogs, with minimal atrioventricular node and atrial involvement. Significant proximal right bundle branch fibrosis was observed in the two dogs receiving one or two additional shocks. We conclude that the suction electrode catheter permits repeated His bundle recording, pacing, and ablation with a single catheter. Permanent and safe low-energy ablation of the canine His bundle is feasible. Focal injury localized to the target area in the conduction system can be obtained.

Animals↗
PubMed1986

Congenital abnormalities of the conduction system in sudden death in young adults.

The sudden death of four apparently healthy young people, three men aged 25, 24 and 21 years, respectively, and one woman aged 20 years, was investigated. The heart was of normal size in two and was slightly enlarged in two. The conduction system in all hearts was serially sectioned. In all hearts the His bundle showed loop formation. In two, the branching bundle was left-sided with the right bundle branch intramyocardial. In the other two, the His bundle was markedly fragmented. Two had myocarditis, and three had arteriolosclerosis of the summit of the ventricular septum. These findings suggest the following: autopsy may be otherwise normal or show minimal findings in cases of sudden death in young people, with significant abnormalities seen only in the conduction system. The common denominator in the conduction system may be a congenital abnormality of the His bundle (in two hearts it was fragmented, in two it was left-sided and there was loop formation in all). Acquired changes may be present, such as arteriolosclerosis of the summit of the ventricular septum (three cases), myocarditis (two cases), and fatty infiltration in the atria (all four cases), a congenital abnormality of the His bundle with or without other findings (congenital or acquired) may cause reentrant phenomena or increased automaticity, ventricular arrhythmias and sudden death.

Adult↗
PubMed1986

Long-term follow-up of cardiac rhythm in repaired total anomalous pulmonary venous drainage.

Seven consecutive patients with total anomalous pulmonary venous drainage were operated at the Medical College of Ohio at Toledo and long-term follow-up is reported on their rhythm status. The patients were generally under 3 months of age at operation. All patients are alive at the present time. The median length of follow-up is 4 years. Five of the 7 patients demonstrated ectopic pacemaker activity and 2 exhibited episodes of nodal rhythm as well. In general, these were not apparent on standard screening electrocardiography. There was no correlation between the presence or absence of this arrhythmia and the type of repair. It is concluded that arrhythmias may be present in these patients, but that they are unrelated to the type of surgery performed. The ectopic atrial focus may be of no clinical significance but there is more cause for concern in those patients with nodal rhythm.

Arrhythmias, Cardiac↗
PubMed1986

Histologic changes and arrhythmogenicity after discharge through transseptal catheter electrode.

Ventricular tachycardia commonly arises within the intraventricular septum and successful catheter ablation of septal tachycardia might be enhanced by transseptal electrode placement. We have evaluated the safety of a transseptal ablation procedure. Arrhythmogenicity and histology were examined after high-energy capacitor discharges were delivered to an intracavitary cathode-anode pair placed on opposite sides of the interventricular septum in pentobarbital-anesthetized dogs. After two discharges of 200 or 100 J proved lethal, paired discharges of 30 or 50 J (10 dogs) or a single discharge of 100 J (four dogs) was used to induce 28 lesions. Acute rhythm changes and risk of induction of ventricular tachycardia by programmed stimulation were measures of arrhythmogenicity. Gross and histologic examination of the hearts after 20 min to 28 days allowed characterization of the evolution of lesions. The conduction system in nearby and remote locations was extensively examined in four dogs. Refractory ventricular fibrillation developed with paired shocks at 200 or 100 J. At lower energy levels, acute ventricular fibrillation occurred with 12 of 20 shocks (60%), but defibrillation was consistently achieved. After ablation, no dog had ventricular tachycardia or fibrillation induced with programmed stimulation. Matching anodal and cathodal lesions spanned the septum without perforation in 10 of 16 dogs, and the lesions were of similar histology. Each contained central areas of hemorrhage surrounded by a region of coagulation necrosis merging with normal myocytes peripherally. There was necrosis and edema without inflammation at 20 min, acute inflammatory cell infiltration at 1 to 2 days, and myocyte replacement by granulation tissue after 6 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Conduction system in cases of sudden death in congenital heart disease many years after surgical correction.

The conduction system and the entire heart were examined histologically in four patients with congenital heart disease who had surgery many years before they died suddenly. All were asymptomatic, in sinus rhythm and living normally. The sudden death may have been related to alterations in the conduction system, previously present, or introduced by the previous surgery, or related to inflammatory phenomena, an outgrowth of the previous surgery.

Adult↗
PubMed1986

The surgical anatomy of the heart in tubular hypoplasia of the transverse aorta (preductal coarctation).

Two hundred nineteen hearts with preductal coarctation (tubular hypoplasia) were analyzed in the laboratory to aid in surgical correction. One hundred fourteen were without and 105 were with ventricular septal defect. We believe the following anatomic findings may be responsible for the mortality and morbidity in surgical repair. The smallness and thinness of the left atrium (40% in those hearts without and 24% in those with ventricular septal defect); the smallness and thinness of the left ventricle (46% in those without and 32% in those with ventricular septal defect); the presence of mitral stenosis (35% in those without and 24% in those with ventricular septal defect); the presence of unicuspid or bicuspid dysplastic aortic valve (49% in those without and 50% in those with ventricular septal defect); the presence of a combination of aortic and mitral stenosis (22% in those without and 9% in those with ventricular septal defect); the location of the ventricular septal defect when present; and the possibility of stenosis or insufficiency of the dysplastic aortic valve in the late postoperative period.

Aortic Coarctation↗
PubMed1985

Electrophysiologic and anatomic changes in the atrioventricular junction of dogs after direct-current shocks through tissue fixation catheters.

Barb-tipped fixation electrode catheters were inserted under fluoroscopic control in the region of the atrioventricular (AV) node in 6 dogs. A series of direct-current shocks (20 to 240 J) were delivered from the electrode catheter to a back plate. Serial electrophysiologic studies were performed before and 2 to 3 weeks after delivery of the shocks. In general, low-energy shocks--20 to 180 J--resulted in predominant damage to the approaches to the AV node, the AV node and common bundle, whereas larger shocks created diffuse damage involving the His bundle and bundle branches. Despite histologic damage to the AV junction, only minimal changes in AV conduction were observed. Thus, there is a large safety margin for AV conduction.

Animals↗
PubMed1985

Study of the conduction system in a population of patients with sudden infant death syndrome.

The conduction system of 23 infant hearts, 15 of sudden infant death syndrome (SIDS) and eight of those dying from known cause, was serially sectioned. A left-sided His bundle was found more commonly in (SIDS) (eight of 15) than in the controls (two of eight). Taking into account a previous study in which a left-sided His bundle was found in only four of 32 hearts from all age groups, this is statistically significant and may be a factor promoting SIDS.

Atrioventricular Node↗
PubMed1985

Truncus arteriosus with interrupted aortic arch: report of a successful surgical repair.

The association of truncus arteriosus with interrupted aortic arch represents a formidable surgical challenge. Two successful repairs have been reported, but none for the past ten years. This report presents a third successful repair using a technique that allows the widely patent ductus arteriosus to maintain continuity between the truncus (with pulmonary arteries detached) and the descending aorta. Right ventricle-pulmonary artery continuity is established in the usual way with a porcine-valved conduit. While long-term potential difficulties with this approach are recognized, it appears to give satisfactory initial palliation and to be an acceptable method of treatment for this combination of defects. The embryology and the anatomy of the lesion are briefly discussed.

Aorta, Thoracic↗
PubMed1985

Functional aortic valve atresia in transposition of the great arteries.

The criterion for the diagnosis of functional atresia of a patient semilunar valve is met when the pressure in a ventricle remains lower than that in the related great artery throughout systole so that no forward flow can occur. Functional pulmonary valve atresia has been well recognized in infants with normally related great arteries and massive tricuspid valve incompetence. The cardiac physiology and anatomy of an infant with transposed great arteries and functional aortic valve atresia is reported for the first time. The peak systolic pressure in the right ventricle was 30 mm Hg and in the aorta 64 mm Hg. The causes for right ventricular incompetence were abnormalities of the tricuspid valve and hypoplasia of the ventricular free wall. Three other cases with similar ventricular anatomy and physiology but with anatomic atresia of the aortic valve are reviewed. The possibility that under these physiologic circumstances during fetal life functional atresia develops first, and that anatomic fusion of idle semilunar cusps develops as a secondary phenomenon, is discussed.

Aortic Valve↗
PubMed1985

Isolated prolapse of the tricuspid valve.

Tricuspid valve prolapse has remained a poorly defined entity. Some authors have stated that prolapse isolated to the tricuspid valve has not been documented. This report contains three cases of isolated tricuspid valve prolapse including the first pathologically confirmed case. A review of worldwide literature including all reported cases of isolated tricuspid valve prolapse is also presented. Although signs and symptoms are similar to those found with mitral valve prolapse, tricuspid valve prolapse may occasionally be differentiated by auscultation. The diagnostic criteria of tricuspid valve prolapse are thoroughly discussed for each of the presently available invasive and noninvasive techniques. Right heart catheterization can define such prolapse but is invasive and requires meticulous technique. Two-dimensional echocardiography supersedes M-mode because of the superior spatial evaluation of the tricuspid leaflets in relation to the right atrium and ventricle. Multiple views including a long-axis view of the right ventricular inflow are often required. This parasternal echocardiographic window is often the only one which permits adequate visualization of the posterior leaflet. The pathologic findings of tricuspid valve prolapse are similar to those of mitral valve prolapse. This report concludes with a description of associated conditions. Severe tricuspid regurgitation has not been noted with tricuspid valve prolapse in the absence of superimposed disease, yet much remains undefined concerning the clinical significance of this condition.

Aged↗
PubMed1985

The conduction system in patients with a prolonged QT interval.

The conduction system and the myocardium of five patients with Romano-Ward syndrome and one patient with the Jervell and Lange-Nielsen syndrome were studied to determine the cause of the prolonged QT interval. The patients were 9 and 15 months and 2, 5 and 19 years of age, respectively. All had a prolonged QTc interval. A sixth patient was a 16 year old girl who died suddenly; several members of her family had a prolonged QT interval. The only common finding in the conduction system in all cases was marked fatty infiltration in the approaches to the atrioventricular (AV) node. In four, the AV bundle was lobulated, with loop formation in one. In four, the AV bundle and bundle branches showed fibrosis. The ventricular myocardium in all cases was chronically inflamed. In two cases, the AV node was partially embedded in the central fibrous body. It is not clear how these changes are related to the disturbance in the repolarization process and the prolongation of the QT interval. However, it is interesting that all patients had an abnormality in the conduction system.

Adolescent↗
PubMed1985

Sudden death after catheter-induced atrioventricular junctional ablation.

Atrioventricular (AV) junctional ablation was performed in a 59-year-old woman with recurrent atrial fibrillation refractory to treatment with digoxin, beta-blockers, verapamil, quinidine, procainamide, and amiodarone. She received two shocks of 500 J which produced complete AV block. After six weeks, both 24-hour ECG recordings and an exercise tolerance test showed infrequent premature ventricular complexes, 3 degrees AV block, and paced ventricular rhythm with 100 percent capture. She suddenly collapsed and was found to be in ventricular fibrillation and could not be resuscitated. Serial sections of the conduction system showed marked fatty infiltration of the approaches to the AV node with almost complete separation from the node. A partially fibrosed atrioHisian connection was also present. Fibroelastosis with chronic inflammatory changes was present in the AV node, bundle of His, and right and left bundle branches. In addition, marked inflammatory changes with fibrosis were present in the atrial septum, in the summit of the ventricular septum, with degenerative changes in the tricuspid and aortic valves. The sequelae of these findings outside the conduction system in other patients remains to be determined.

Atrial Fibrillation↗
PubMed1984

Microtransection of the His bundle with laser radiation through a pervenous catheter: correlation of histologic and electrophysiologic data.

This study describes microtransection of the His bundle with a pervenous laser catheter in a live dog. In an adult mongrel dog anesthetized with Nembutol , administered intravenously, electrode catheters (No. 5Fr and 6Fr ) were inserted through a femoral vein and positioned in the high right atrium for atrial pacing and in the His bundle region for recording of His bundle electrograms. The AH and HV intervals were measured during normal sinus rhythm and atrial pacing. Through another femoral vein, a laser fiber was inserted through a lumen catheter (No. 7Fr ) with a preformed curved tip. Under fluoroscopic control, the laser fiber tip was positioned immediately next to the His bundle electrode catheter. During continuous His bundle recordings and fluoroscopic monitoring, short bursts (10 to 60 seconds) of argon laser were delivered (2.5 W) in order to produce His bundle interruption and complete heart block. Escape of a His bundle rhythm (cycle length = 1,100 ms) with QRS morphologic characteristics and duration similar to that of normal sinus rhythm was noted. "Split" His bundle potentials were recorded with an unchanged AH (50 ms) and an H'V interval of 20 ms. After the dog was killed, serial sections of the conduction system of the heart were analyzed. Histologic findings showed excellent correlation with electrophysiologic observations and validated "split" His bundle potentials. The laser radiation produced microtransection of the His bundle with a channel of tissue dissolution 0.2 to 0.3 mm wide in diameter. The latter passed through the His bundle at the junction of penetrating and branching segments, dividing it into superior and inferior portions that retained continuity with proximal and distal His bundle.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗